1. Field of the Invention
The present invention relates to a central control system of air conditioners including a central control unit that transmits and receives data to and from a plurality of air conditioners over a network and can perform central control of operations of the air conditioners, and more particularly to a central control system of air conditioners and a method for operating the same, wherein the central control unit is connected with a power meter for measuring power consumption of the plurality of air conditioners in operation, thereby achieving efficient management and calculation of electricity charges.
2. Description of the Related Art
Demand for air conditioning systems for providing air conditioning in a building is on the rise. Such air conditioning systems are mainly divided into two types. One type is a single-type air conditioning system suitable for providing air conditioning in a small room, and the other is a multi-type air conditioning system that is installed in a large building and allows cooperative management.
As shown in FIG. 1, the single-type air conditioning system includes indoor units 10 installed respectively in rooms and outdoor units 20 that are installed outdoors and connected respectively to the indoor units 10 for circulation of refrigerant. Users separately install and operate air conditioners (each including an indoor unit and an outdoor unit) of the single-type air conditioning system respectively in their rooms of a small building or the like where cooperative management is unnecessary.
On the other hand, the multi-type air conditioning system includes a large number of indoor units installed respectively in rooms and a small number of outdoor units, connected to the indoor units, for distributing refrigerant to the indoor units and controlling circulation of the distributed refrigerant according to input control commands. To accomplish this, the outdoor units monitor in real time operating states of the large number of indoor units.
The multi-type air conditioning system has an advantage over the single-type air conditioning system in that it saves installation space of the outdoor units. The multi-type air conditioning system also has an advantage in that i-t can decrease total power consumption for air conditioning since the large number of indoor units are managed and controlled by the smaller number of the outdoor units, thereby increasing management efficiency.
However, such air conditioners, which circulate refrigerant for providing air conditioning, increase the burden of paying electricity bills since power consumption for starting the air conditioners and power consumption for maintaining operations thereof are very high due to their basic characteristics, compared to other home electric appliances. In addition, in the case where the plurality of indoor and outdoor units of the single-type air conditioning system or the multi-type air conditioning system are installed over the entirety of a building, it is more difficult to perform power management.
An electricity utility company assigns upper power limits (i.e., maximum allowable power consumption levels) to buildings, where the upper power limits vary depending on seasons/time zones/regions. If power consumption exceeds the upper power limits, the electricity utility company charges progressive electricity rates, which increases management costs.
If a fuse of the air conditioning system blows due to an abrupt increase in the peak power consumption, the entire power of the building is cut off, which may cause a physical impact on home electric appliances in use, lowering endurance of the appliances.
Accordingly, the manager of a building, where the plurality of indoor and outdoor units of the single-type air conditioning system or the multi-type air conditioning system are installed, uses a power meter (for example, a watt-hour meter) 30 as shown in FIG. 1 to check power consumption during a predetermined period of time and thus to perform power management for allowing the power consumption to be limited below the upper power limit. Such a check of power consumption also makes it possible to anticipate management costs.
However, the power meter 30 in the conventional air conditioning system can only measure power consumption of all of the electric appliances, including the air conditioners, in the building or can only measure power consumption of the entire air conditioning system. That is, the power meter 30 cannot measure accurate power consumption of each of the indoor units 10 installed respectively in the rooms of the building, making it impossible to perform accurate calculation of electricity charges and accurate division of total electricity charges into respective electricity charges of the rooms.